1. Field of the Invention
This invention relates to methods to support process quality and maintenance during control of an industrial process such as welding.
2. Background Art
Traditionally, large-scale resistance welding networks for use in assembly facilities can cost between $250,000 and $900,000 to install, not including configuration. U.S. Pat. No. 5,808,885 discloses a weld controller coupled to a communications network which has an operator interface unit for monitoring and controlling the weld controller and other weld controllers on the network. A common database in the operator interface unit is accessible across the communications network by the weld controller. The weld controller can use the database to obtain different weld schedules, duplicate its own weld schedule to provide for easy replacement, and as a data storage for its operating parameters and values. The weld controller has a dual communications port that allows for a variety of operator interface configurations. Data from the weld controller can be accessed by the operator interface controller based upon the weld controller's individual data structure and type through embedded objects resident in the operator interface's operating system and program. The data can then be displayed, edited, and stored by any data entry device that is capable of executing the operator interface's program.
The promise of these welding networks is cost savings and better control of the facility. These networks, however, typically fall short of their expectations, become “Boat Anchors” and fall into disuse or are used as nothing more than central programming stations. There are several reasons that these networks fall short of expectations.
Islands of Automation
The network hosts that are typically provided are islands of automation. They provide access at one or at best a limited number of terminals available in the plant.
Require Active Management
Existing networks have no means for informing the user of an existing or pending problem. The user must know that a problem exists or review the data at the network terminal regularly in order to determine whether action is required.
Do Not Provide Data Reduction
No means for automatic data reduction is provided. Often the user is required to wade through mountains of meaningless faults and events to determine what is relevant.
No Process Control Support
Existing networks tend to be organized around the weld control and not the process. This is not surprising since existing welding networks are the products of the welding control companies, but it is not acceptable. Much more useful from a process standpoint are facility-wide reports and data presentation.
No Administrative Support
Existing networks provide no tools for administration of the plant. They provide no assistance in configuration and administering the welding network on a plant-wide basis. No facilities for limit-setting or auditing are provided.
No Maintenance Support
No facilities for predictive or preventative maintenance are provided. At best, one can look at the stepper status and determine if the caps require changing. In addition, there are no facilities for determining the degradation or the capability of the system at any point in time.
No Quality Systems Support
Existing networks provide no support for quality systems. There are no facilities for change control, maintaining mandated quality information or auditing the system for compliance.
Once the user tumbles into these shortfalls, the network becomes much less useful and the systems falls into disuse.
For instance, if the network does nothing to assist with maintenance, the user has no choice but to reactively address problems reported from the floor. Once the problem is reported, the clock is ticking, as there is probably downtime associated with it. There is no need to locate a network terminal and consult it, as this will most likely only increase the downtime. The most effective course is to go directly to the site of the problem, determine its cause and repair it. This totally leaves the network out-of-the-loop.
Other than providing centralized programming, the existing network solutions do little to simplify the user's tasks. As such, they quickly fall into disuse and become an expensive “Boat Anchor.”